Rhynchospora oligantha |
Rhynchospora fusca |
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featherbristle beaksedge |
brown beaksedge, rhynchospore brun |
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Habit | Plants perennial, densely cespitose, knottybased, 20–40 cm; rhizomes absent. | Plants perennial, cespitose, 10–50 cm; rhizomes stoloniferous, slender. |
Culms | filiform, leafy at base, wiry. |
erect to excurved, filiform, leafy, ± terete. |
Leaves | ascending to erect; blades filiform, nearly terete, or channeled, sometimes compressed, nearly reaching distal inflorescence or much shorter, 0.2–0.3 mm thick, apex subulate. |
shorter than culm; blades ascending, filiform, proximally to 1.5(–2)mm wide, apex trigonous, tapering, setaceous. |
Inflorescences | spikelet clusters 2–6, simple or reduced to 1 spikelet, branches ascending to divaricate or reflexed; leafy bracts single per cluster, filiform, setaceous, with clusters appearing lateral to bracts. |
lateral spikelet clusters (0–)1–2, distant, terminal cluster ellipsoid to broadly turbinate or hemispheric, branches ascending; leafy bracts setaceous, overtopping clusters. |
Spikelets | pale redbrown, ellipsoidlanceoloid, 5–6(–8) mm, apex acute to acuminate; fertile scales oblongelliptic, convex, acuminate, 3.5–5 mm, apex broadly acute, midrib forming apiculus. |
red-brown to deep brown, lanceoloid, (4–)5–6(–7) mm, apex acute; fertile scales lanceolate, 4–5(–6) mm, apex acuminate, midrib often excurrent as awn. |
Flowers | perianth bristles 6, reaching to or slightly past tubercle base, increasingly plumose from middle to base. |
bristles 5–6, longest reaching at least past tubercle base, mostly to tip or beyond, antrorsely barbellate. |
Fruits | 1–3 per spikelet, (2.5–)2.7–3(–3.4) mm; body light brown to brown, ellipsoidobovoid, distally conspicuously necked, tumidly lenticular, 1.7–2.5 × 1.5–1.8 mm; surfaces smooth or minutely transversely rugulose; tubercle conicsubulate, 0.5–0.7 mm, base flaring. |
2(–3) per spikelet, (2.3–)2.5–2.6(–3) mm with pedicellar joint, receptacle, and tubercle; body lustrous, pale brown to deep brown, obovoid to ellipsoid, lenticular, 1–1.5 × 1 mm, margins narrow, flowing to tubercle; surfaces longitudinally finely lined, transversely very finely ridged with wavy rows of very narrow, vertical lattices, sometimes also with lines of shallow pits; tubercle triangularsubulate, (0.7–)1–1.3(–1.5) mm, base lunate, margins setulose proximally. |
Rhynchospora oligantha |
Rhynchospora fusca |
|
Phenology | Fruiting spring–summer. | Fruiting summer–fall. |
Habitat | Sands and peats of bogs, depressions in savannas, open pinelands, seeps | Sands and peats of pond shores, bogs, and seeps |
Elevation | 0–200 m (0–700 ft) | 0–400 m (0–1300 ft) |
Distribution |
AL; DC; DE; FL; GA; LA; MS; NC; NJ; SC; TX; VA; Central America; West Indies
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CT; DE; IL; IN; MA; MD; ME; MI; MN; NH; NJ; NY; PA; RI; VT; WI; NB; NL; NS; ON; QC; SK; Europe
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Discussion | Rhynchospora oligantha is distinguished from other taxa of its complex mostly by the distinctive neck at the achene apex, a feature essentially absent in R. breviseta, its closest relative. Those two species have been heavily impacted by conversion of pine savannas to cropland or pine plantations; even with abandonment or clearing of such land, they are very slow to reoccupy the disturbed sites. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 23, p. 218. | FNA vol. 23, p. 232. |
Parent taxa | Cyperaceae > Rhynchospora | Cyperaceae > Rhynchospora |
Sibling taxa | ||
Synonyms | Schoenus fuscus, Phaeocephalum fuscum, R. alba var. fusca | |
Name authority | A. Gray: Ann. Lyceum Nat. Hist. New York 3: 212. (1835) | (Linnaeus) W. T. Aiton: in W. Aiton and W. T. Aiton, Hortus Kew. 1: 127. (1810) |
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